Conventionally, for intervention or angiographic examination, a catheter is inserted through a blood vessel during fluoroscopy of an X-ray image and is moved to a site that has diseases in the heart, brain, liver, or the like. Here, on X-ray images, a blood vessel is visible for a short time only when a contrast media, or the like, is injected so that the structure of the blood vessels become visible to determine relationship between catheter and blood vessels; however, the amount of used contrast media needs to be reduced to prevent the subject from renal impairment.
For example, as the technology for reducing the amount of used contrast media, two-dimensional roadmap function which superimposes a real-time catheter image and pre-acquired blood vessel image is frequently used. Catheter image is created by subtracting pre-acquired fluoroscopic image from real-time fluoroscopic image, and then catheter moved from previous position on pre-acquired fluoroscopic image is enhanced. Blood vessel image is also created by subtracting acquisition image after contrast injection from acquisition image before contrast injection. The two-dimensional roadmap function makes it possible to understand relationship between blood vessels and catheter without using the contrast media and therefore, for example, it is used when a catheter is inserted through a complicated blood vessel, or the like. Here, in a case where the catheter is inserted through a complicated blood vessel, if a two-dimensional roadmap image is used, where a two-dimensional blood vessel image is superimposed on real-time a fluoroscopic image, there is a limitation on understanding of the three-dimensional structure of a blood vessel, and the catheter is sometimes not inserted into the target blood vessel for certain time period.
In such a case, by using a three-dimensional roadmap image where a blood vessel image that is generated from three-dimensional image data with volume-rendering processing is superimposed on a real-time fluoroscopic image, the blood vessel image for three-dimensional roadmap has more detail information than that for two-dimensional roadmap. Moreover, the orientation of the blood vessel image could be changed flexibly and easily so as to see the structure of the blood vessel clearly. However, according to the above-described conventional technology, acquisition of image data for generating a three-dimensional roadmap image is sometimes time-consuming.